Question: Line $m$ is parallel to line $n$ and the measure of $\angle 1$ is $\frac 18$ the measure of $\angle 2$. What is the degree measure of $\angle 5$? [asy] size(100); defaultpen(linewidth(0.7)+fontsize(9));
path m = (-1.35,0.72)--(0.45,0.72), n = (-1,0)--(1,0), k = (-0.67,1.09)--(0.27,-0.48);

pair A = intersectionpoints(m,k)[0], B = intersectionpoints(n,k)[0];
draw(m,Arrows(4)); draw(n,Arrows(4)); draw(k,Arrows(4));

label("$k$",(0.27,-0.48),SE); label("$n$",(1,0),NE); label("$m$",(0.45,0.72),NE);
label("$1$",A,(-2.5,1.5));
label("$2$",B,(1,1));
label("$3$",B,(-2.5,1.5));
label("$4$",B,(-1,-1));
label("$5$",B,(2.5,-1.5));
[/asy]
Solution: Let $x$ be the measure of $\angle 1$, so $8x$ is the measure of $\angle 2$.  Since $m\parallel n$, we have $\angle 5 = \angle 1 = x$.  Since $\angle 2$ and $\angle 5$ together form a straight line, we have $\angle 2 + \angle 5 = 180^\circ$, so $x+8x=180^\circ$.  This gives us $9x = 180^\circ$, so $x= \boxed{20^\circ}$.